JPH0721969B2 - Wire material for audio equipment wiring - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal wiring material for an audio device represented by a stereo device, a speaker cord,
The present invention relates to a wire material for wiring an audio device applied to a microphone cord, a headphone cord and the like.

[0002]

2. Description of the Related Art There is a close relationship between the sound quality of an audio device and the material of the wire used for its wiring. Tough pitch copper for general electric use and oxygen-free copper are mainly used as wire rods of this kind of equipment, and oxygen-free copper is evaluated to give a very excellent acoustic effect.

The present inventors believe that the reason why the wire material using oxygen-free copper is significantly superior in sound quality to the wire material using tough pitch copper for general electricity is as follows.

Metallic copper is normally composed of an extremely large number of fine crystals, and impurities such as oxides and sulfides are gathered at the boundaries between crystals, that is, at the crystal grain boundaries. Tough pitch copper for general electric use contains 100 to 500 ppm of oxygen, which is mainly present in the grain boundaries in the form of cuprous oxide (Cu ₂ O). Since this cuprous oxide is a polycrystalline semiconductor, tough pitch copper for general electrical use contains not only a mere resistance component but also a capacitance component and a detection component, and it is considered that the units composed of these components are three-dimensionally distributed. be able to. This means that when tough-pitch copper for general electrical use is used as a wire rod, it acts as a capacitive reactance for high frequency components, and a music signal, which is a composite signal of many frequencies, is distributed to each frequency component by passing through the system. A phase difference is generated, and human hearing is recognized as phase distortion, which hinders faithful reproduction of sound. Further, the amount of attenuation of cuprous oxide due to the detection action differs depending on the frequency, which also contributes to obstruction of faithful reproduction of sound in tough pitch copper for general electrical use.

On the other hand, oxygen-free copper has a remarkably small amount of oxygen as compared with tough-pitch copper for general electric use, and therefore contains very little cuprous oxide and other impurities, so that faithful reproduction of sound is performed. Factors that prevent

[0006]

However, even if it is assumed that impurities do not exist at the crystal grain boundaries at all, the voids at the crystal grain boundaries still form a capacitance having a dielectric constant of 1. There is an unavoidable phase difference due to capacitive reactance for frequency component signals.

Considering in this way, the acoustic effect of an audio device is governed by the number of crystal grain boundaries of the wire used for its wiring, and the oxygen-free copper containing a very small amount of impurities. However, as long as there are many grain boundaries, faithful reproduction of sound is hindered. Incidentally, as the conventional oxygen-free copper wire rod, an annealed copper wire obtained by annealing a wire rod drawn to a final wire diameter by a wire drawing operation at a temperature of about 400 ° C. is used. The average grain size is 0.02
It is about 0.03 mm, for example, in the case of a 1 m wire rod, about 5
This means that millions of fine crystals are connected in the length direction.

It is an object of the present invention to provide a completely new wiring material for wiring an audio device, which can greatly improve the transmission characteristics of an audio signal containing many frequency components.

[0009]

DISCLOSURE OF THE INVENTION A wire rod for audio equipment wiring of the present invention is an enormous giant crystal grain of oxygen-free copper having an oxygen content of 50 ppm or less so as to have an average grain size of at least 0.4 mm. It is characterized by being made of a crystal wire.

In order to confirm the influence of the crystal grain boundaries on the signal transmission characteristics, the inventors of the present invention prototyped a speaker cord by encapsulating mercury, which is a liquid metal at room temperature without any crystal grain boundaries, in a plastic tube. As a result of conducting a trial listening experiment, it was possible to confirm an excellent sound quality that could not be obtained with the conventional speaker cord. In addition, we asked for listening by an acoustic expert including a renowned music critic, and found that the rise of the sound was extremely fast, the sound image was clear, the dynamic range was wide, the bass was powerful, and the sound was not muddy. , Etc. were highly evaluated.

However, mercury is a harmful substance, and there are many restrictions on its use as a wire for speaker cords. Therefore, it is desirable to use copper without such a limitation, but it is impossible to use copper as a conductor in a completely amorphous state, and as a suboptimal measure, the oxygen content is 50% or less.
When a giant crystal wire made of giant oxygen-free copper crystal grains of ppm or less was used as a speaker cord, the same excellent sound quality as when mercury was used was confirmed, and the present invention was achieved.

The wire rod in the present invention is made of a giant crystalline oxygen-free copper material having an average crystal grain size of at least 0.4 mm.

Since the average crystal grain size of oxygen-free copper used for ordinary wire rods is about 0.02 to 0.03 mm, the crystal grain boundary density is greatly reduced to 1/20 or less in the giant crystal wire rod, The transmission characteristics of the audio signal can be improved.

The giant crystal oxygen-free copper material of the present invention can be easily obtained by a conventionally generally known method.

In the present invention, an oxygen-free copper material having an oxygen content of 50 ppm or less is used, firstly because the signal transmission characteristics are improved by not containing impurities such as cuprous oxide. Secondly, if impurities such as cuprous oxide are contained, these become crystal nuclei to prevent the crystal grains from becoming huge.

The giant crystal wire of the present invention has an average crystal grain size of at least 0.4 mm, and if it is less than this, it is difficult to sufficiently improve the sound quality effect.

[0017]

Example: Oxygen content of 5 ppm and average crystal grain size of 0.4
An insulated electric wire was manufactured by extrusion-coating the outer periphery of a copper wire having an outer diameter of 1.8 mmφ made of an oxygen-free copper material of 0.5 mm with a polyethylene insulator.

[0018]

[Comparative Example] Oxygen content of 5 ppm and average crystal grain size of 0.0
An insulated wire was manufactured by extrusion-coating the outer circumference of a copper wire having an outer diameter of 1.8 mmφ made of an oxygen-free copper material of 2 to 0.03 mm with a polyethylene insulator.

The insulated wire 3 m according to the embodiment and the comparative example is used to connect the speaker and the power amplifier of the stereo device.
In addition, the following is the evaluation when 1 m is used for the connection between the power amplifier and the preamplifier and the reproduced sound of the stereo code is sampled.

Equipment used Preamplifier Sony TA-E900 Power amplifier Sony TA-N901 Speaker Sony APM-6M Player Sony PS-X9 Evaluation method In each case where 10 audio experienced persons were selected and the insulated wires of Examples and Comparative Examples were used. The reproduced sound of No. 10 was blindly heard and 10 sound quality evaluation items were evaluated. The evaluation was performed by dividing each of the sound quality evaluation items A to J into five levels as shown in Table 1 and giving a score of 2, 1, 0, -1, -2 to each.

For each of the examples and comparative examples,
The average of the evaluation points given to the J item was determined, and the difference between the average evaluation points of Example 1 and Comparative Example and the difference of Example 2 and Comparative Example are shown in Table 2.

[0022]

[Table 1]

[0023]

[Table 2]

As is clear from Table 2, the giant crystal wire of the present invention is superior to the conventional oxygen-free copper wire in all the items of human sensory evaluation.

[0025]

As described above, according to the present invention, a wire rod for audio equipment wiring is constituted by oxygen-free copper having a large crystal grain, and the grain boundary density in the length direction is diluted. As a result, the capacitive reactance caused by the crystal grain boundaries can be made extremely small, and it becomes possible to make the phase variation and the amplitude attenuation uniform with respect to a signal including a large number of frequency components. Therefore, extremely high quality sound can be realized.

Claims (1)

[Claims] 1. A wire rod for wiring audio equipment, comprising a giant crystal wire rod obtained by enlarging crystal grains of oxygen-free copper having an oxygen content of 50 ppm or less to have an average crystal grain size of at least 0.4 mm. .